A green investment bank, designed to make the transition to a low-carbon economy, has been confirmed in the spending review. Photograph: Martin Godwin

On the face of it, the Department of Energy and Climate Change (Decc) came out of the carnage better than expected: a 30% cut in administrative costs but just 5% annual cuts for four years, and capital spending increased. Promises of big money were made for renewables and carbon capture and storage, and a new green investment bank was confirmed.

But if the winners were technologists and big businesses, the losers appeared to be the poor, who will see energy efficiency grants designed to improve fuel poverty slashed.

Businesses welcomed the setting up of a green investment bank, designed to unlock private sector funds to stimulate green business and make the transition to a low-carbon economy.

The energy secretary, Chris Huhne, wants the bank to have up to £6bn of funds and crucially to be able to raise many billions more of private-sector financing to achieve the £200bn investment in new electricity grids, power stations and windfarms required in the next decade. The Treasury wants the bank to act like a limited fund and is opposed to any government-backed borrowing.

Debate over the future of the green investment bank continues to rage in Whitehall, despite the chancellor's announcement that it would receive £1bn in public funds and proceeds from future asset sales. This morning the deputy prime minister, Nick Clegg, wrote to Liberal Democrat MPs telling them that the government had provided £2bn. One Whitehall source told the Guardian: "The budget was £2bn at breakfast time on Tuesday, but only £1bn by lunchtime."

"Energy companies will be disappointed by the initial funding for the green investment bank. The £1bn is a tiny sum compared with the annual level of investment required in new energy infrastructure, so they will be looking more to the promised energy market reform to drive new investment," said Richard Gledhill, climate change partner at accountancy firm PwC.

"Although £1bn sounds a lot, it may not be enough to leverage the billions of pounds of extra private-sector cash needed to kickstart the low-carbon revolution," said Tim Yeo, who chairs the energy and climate change select committee.

One sting in the tail for business was the decision to plough money collected from large businesses under the so-called Carbon Reduction Commitment scheme back into Treasury coffers "to support the public finances". The original plan had been to redistribute the cash to businesses that did most to cut their carbon emissions, so the move – which was not specifically referred to in the chancellor's announcement – will be seen by many in business as a stealth carbon tax.

Environment groups accused the government of deserting the poor for dismantling the £280m Warm Front initiative after 2011. This provided means-tested grants for energy efficiency measures such as home insulation.

Although the Renewable Heat Incentive (a similar scheme due to be introduced next June) was scaled down by 20% from its original projections, the new £860m scheme to reward companies who invest in renewable energies was widely welcomed.

"This is excellent news for the UK solar industry. It's exactly what the market needs in order to fulfill its fantastic potential. The outcome of today's review could not have been better," said Ray Noble from the Renewable Energy Association.

£200m will go to stimulate UK-based offshore windpower, but the most financially ambitious initiative announced yesterday was to spend "up to" £1bn on a single commercial-scale carbon capture and storage (CCS) plant for a coal power station. Four such plants were originally planned as part of the government's CCS competition.

"This gives certainty to the market and ordinary people will gain, too. This will provide a strong boost for green jobs. I would be very surprised if we did not get much more than the £1bn promised for the green investment bank," said the climate minister Greg Barker.

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